ajax code does not work on IE8

[doforumda]

hi
i wrote a code for login. it uses xhtml, ajax and php. the problem is when i try to login using firefox and chrome it does log me in and working fine but when i check it on IE8 and safari it does not log me in. it just displays loader and does not process the code and does not log me in.

what am i doing wrong in this code. help please

$(document).ready(function () {
	//This is function triggers when login button is clicked.
	$('#loginbtn').click(function (){
		hideshow('loader',1);
		var url = "login.php";
		//var queryString = $("#login_form").serialize();
		var email = $('#email').val();
		var password = $('#password').val();
		var queryString = 'email=' + email + '&password=' + password;
		//alert(email);
		//alert(queryString);
		$.ajax({
			type: "POST",
			url: url,
			data: queryString,
			dataType: 'json',
			success: show_login
		});		
	});
	
	//This function triggers when loginbtn process is successfully completed.
	function show_login(resultData) {
		//alert(resultData.error);
		if(resultData.error=='no') {
			$('.error').css('visibility','hidden');
			$('#login_form').submit();
			hideshow('loader',0);
		}
		else {
			hideshow('loader',0);
			$('.error').html(resultData.fieldErrors).css('visibility','visible');
		}
	}
});